Maybe Sidney wasn't going to be in Scream 5.....
Just out of boredom I was daydreaming about the never-to-be Scream 5 and 6 that were originally planned.
Now in the original script we all know the ending was Jill being rushed off to the ambulance outside Kirby'a house when suddenly a Woodsboro Officer comes calling out that someone, a female, is still alive. End of. Cliffhanger leading straight into S5.
Now everyone of course instantly presumed this ambiguous female survivor was Sidney (and it probably was intended to be) BUT what if it wasn't...
What if the female survivor was Kirby? Her death always seemed a bit mysterious. To this day I don't think any of us can really 100% be sure if she bled to death or not we just use the fact there hasn't been a Scream 5 to cement her death in Scream history.
Remember Kirby never knew Jill was the killer. She just saw Charlie and once recovered she would have no reason to doubt Jill's story that Trevor was the second killer.
So the fifth film could've originally been about Kirby, Dewey and Gale slowly figuring out that Jill was the Woodsboro 2.0 killer while (I'm guessing) a whole new set of murders were happening around them.